We have a PA-25-235, Lycoming O-540 with fixed pitch prop. At the last
rebuild we used the STC and pumped it up to 250HP. We tow from apx 3000MSL
airport on 110F days with no problems. In the winter (40-50F) we start
leaning just above pattern altitude. In the summer.. about 500ft AGL.

Technique, When the RPM starts to drop during the climb, lean to get the RPM
rise and leave it, your climbing so you will get richer with more altitude,
then lean again. Full power climbs. At release, Left turn and nose over to
about 80-100, depending on turbulence, and reduce power to maintain 2400rpm,
don't touch the mixture. Faster airspeed, no load on the prop, rpms
increase, slow reductions in power setting, 2200, 2000, 1800, etc into the
traffic pattern, plan the pattern so as to not have to level off and
increase power to maintain altitude. I normally enter the downwind at 1000ft
and may be down to 500ft when I turn a close in base leg, power back to
about 1500 rpm, airspeed slowing (nose attitude change) to 70 and 60 on
final. I don't touch the mixture until the next take off, or full power if a
go around is needed.

Other techniques include rolling to steep bank, and pulling G while
maintaining airspeed with nose on the horizon (rudder) control. Can get
descent rates of over 2000fpm, it helps coming down from a high tow while
maintaining cooling.

Others on their warm up flight will determine the mixture position to get
max rpm in level flight at normal release altitudes. Using the same leaning
technique in the climb, but will reset the mixture to the predetermined
position for the descent and using the "staged cooling" process. Again,
planning the descent into the traffic pattern to not have to level off on
downwind, a continuous descent to earth.

BT


"Tim Hanke" wrote in message
ups.com...
We have acquired a 260 hp Pawnee for a towplane and was wondering what
others are doing for cool down after the sailplane releases...


Thanks,

Tim Hanke
Adirondack Soaring Group
Saratoga Springs, NY